Do hens suffer from depression?

I recently had to cull one of my pullets, a B.O, and a friend said I could have one of hers. We don't know how old she is but she is at least three years older than my 4 mo. old flock of five. She is probably pretty old and as far as I know has been in one flock all her life.
So I plucked her away from her family and put her with my youngsters. Its been about three weeks now and she still stands alone and spends a lot of time roosting. She's eating and preening but I haven't seen her scratching or dust bathing.
She just looks depressed. I feel so sorry for her. Do you think she will get over it and join the flock?

Chickens do get attached to their flockmates and their owners. Can you give her any special treats to spoil her a little? Was there anything special she liked or was used to getting at your friends house? When parrots are rehomed or go into rescue, it gives them a lot of comfort to have foods, toys or little activities that they were used to in their previous life. I would think it would make chickens feel good to have something familiar, too. And they do love food!

Unfortunately she's showing no interest in anything, not even treats. This afternoon she has been standing facing the tree trunk, her back to the world and the pullets...for three hours.
Maybe I should take her back. I just keep thinking its just a question of time, but this is heartbreaking.

Poor thing! If it possible that she didn't have the same immunities are your flock and may have gotten sick as a result? If you do take her back, it'll be important for your friend to isolate/quarantine her for a while to make sure she's not ill.

This may sound silly, but, here goes: Maybe she has nothing in common with the rest of the flock. I guess depression can happen to any animal if it's removed from the only surroundings it's ever known. I'm not a chicken psychologist (I'm sure if there is a dog whisperer, a horse whisperer, etc., etc., there will soon be a chicken whisperer), but it's my guess she's just....bored.

That's a sweet thought, not silly at all. Maybe the age difference is too big, maybe all the teenage chatter drives her crazy and she just wants some peace!
I have just noticed that her poo is very green and watery with undigested bits of lettuce in it. She probably isn't used to so much greenery, she might not be feeling too well either.
Anyway, both helpful suggestions, thank you.

Hmm... That sounds like she may not be feeling too well. I'd keep an eye on her and watch her closely for any other possible symptoms that may develop. Stress from changes can suppress the immune system and sudden dietary changes can cause temporary digestive upset. Poor girl. I hope it's nothing more serious.

Do you think a little yogurt as food or a small amount of apple cider vinegar in her water, would help the bacterial balance in her digestive system? Both should be in the unpasteurized form, with the live cultures.

I have four hens two older nes and two younger ones there is a about a year or two between them well anyway one of the older ones has recently passed and the remaining elder acts exactly like this down to the green poo only she is broody so I've been taking her out and putting her in a cold bucket of water she gets herself out and then act like the hen you described and I'm sur it was brought on by the death of her flock mate

She did grow up with the other hen I took two of them from a meat farm and the other two later on from a school hatching project